Inside Vostok’s Atlas, the quad filter module impressed by 80s Roland

80s Japanese synths just like the SH-101, JUPITER, JUNO, and TR drum machines have been outlined by each their filters and the engineering round them. We’re lucky to speak to Vostok Devices in regards to the design of their new four-channel Atlas filter module – what it learns from the 80s classics, and what it provides to the equation.

The Atlas Quad Core Multimode filter was within the deluge of latest gear late final month, nevertheless it deserves some particular point out. It’s no secret that in these CDM elements, we’re all enamored of the unique Dave Rossum-designed SSM2164 chip and the trendy redesign true to that unique, the Sound Semiconductor SSI2164. That new SSI chip is now discovering its manner into quite a lot of gear for a motive. (And should you don’t know your IC elements, don’t fear – you’ll know the devices that used them.)

The Atlas is an particularly enticing design for bringing that chip into the modular world. You get 4 filters on Atlas:

The cores are a contemporary method to the gain-cell-based filters included in lots of the traditional Japanese synths of the 80s, with a vastly improved dynamic vary, a super-accurate resonance compensation circuit, and a clear self-oscillation. It’s excellent for recreating iconic TR-drum sounds by pinging the filters with quick envelopes or triggers.

Simply having 4 filters with CV management is cool, however the added sauce is the power to morph between all filter outputs, creating some timbres and shapes you couldn’t get earlier than. That’s by way of a devoted Interpolating Scanning Circuit that handles the morphing, plus a properly accessible scanning fader and CV management.

Options onboard Atlas:

  • 4 filters, every with lowpass, highpass, and bandpass modes
  • Steady resonance management
  • CV management of filter cutoff
  • CV management switchable between frequency (FM2) or resonance (set to frequency, the 2 frequency controls are summed)
  • Scan CV enter for controlling filter scanning (morphing)
  • Devoted fader for scanning by filters

And sure, with filter inputs on every, you’ll be able to ping any (or all) of the filters with alerts, superb for percussive sounds.

The 4 filters are daisy-chained, too, by default – patch a cable on the enter to interrupt the chain. That opens up some good parallel filtering choices.

All of that is 280€ pre-tax; avenue worth is much less. Good Circuit has Atlas out there now (on preorder):

When you purchase one thing from a CDM hyperlink, we could earn a fee.

Atlas Quad-Core Multimode Filter

Extra on Atlas:

16HP, however you get a lot of motion out of that 16HP. I talked to Vostok’s Jose Angel Cabrera extra in regards to the design work that went into this. Jose tells CDM:

The filter cores are designed across the SSI2164 IC by Sound Semiconductor, a contemporary redesign of the traditional SSM2164 designed by Dave Rossum, which has an improved dynamic vary and low distortion. That was key to me as a result of I really like the clear sound of one of these filter, however in a number of designs the dynamic vary is proscribed to forestall the filter from distorting, flattening the sound of the filter, and dropping character.

I labored lots in Atlas cores to get a steadiness between a very good quantity of dynamic vary and a really low distortion. The filters can sweep freely at excessive resonance ranges. They’ll go loud if they should. I didn’t restrict the output ranges to allow them to transcend the usual +/-5V, however you hardly will hear it distort. That, summed with the compensated resonance circuit, offers quite a lot of character to the filter as a result of the passband is all the time there. For most individuals, it’s extra noticeable within the low-pass mode since you don’t lose the bass, nevertheless it additionally makes the high-pass sound nice because the sound retains its air and brightness.

The Interpolating Scanner relies on the unique Jurgen Haible circuit and the later improved model by Donald Tillman. The aim of the circuit is to consecutively flip transistors ON and OFF with an exterior CV to create a present line that drives a number of VCAs.

I breadboarded these circuits years in the past and located them very fascinating to pair with filters nevertheless it was arduous to discover a good compromise between a clean form that enables center middle-points between the channels and in addition retaining a homogeneous achieve curve, so I made a decision to start out from the scratch and make my model of the circuit. The Atlas scanner has a really clean fading slope with an precisely matched conduct on the channel touring, so it feels good if you go throughout totally different filter mixtures. It additionally makes use of the identical chip I take advantage of on my six-channel VCA module Ceres, the AS3360, a contemporary revision of the traditional Curtis CEM3360. The 3360 is a nice-sounding VCA chip with intelligent and optimized linearization, which is vital on this design as we wish to protect the scanning form intact.

I personal an SH-101, my favourite synth of all time, and I labored with tons of essentially the most iconic Roland synths of that period, just like the SH-2, Jupiters, Junos, TRs, and many others. I’m very impressed by these schematics, and I discovered lots from them. The Atlas filters are a compendium of all the pieces I like from these synths, with extra trendy strategies and parts which have a constructive affect, not solely on the sound but additionally on different issues like energy consumption. Atlas energy consumption is 170mA, however counting the variety of VCAs and OPAmps the module makes use of, the low distortion configuration of the circuit, and the truth that it has 4 completely devoted multimode filters and a scanning financial institution, it is rather environment friendly.

I’m glad you favored the design! It is among the most essential issues for me. I’m an enormous fan of unpolluted interfaces that assist usability, which I attempt to expose in my modules. I’m not planning on doing a narrower model of Atlas, however I like the thought. Whereas it’s not a little bit module (16HP), I feel it is rather HP environment friendly since you get 4 filter blocks plus the scanning in 16HP, with the helpful cascade enter perform that avoids the necessity for a a number of (or let those you have already got free), and in addition reduces the variety of patch cables wanted for some patches.

In fact, house nerds will instantly be aware that it is a module from Vostok, the Soviet R-7-derived rocket that launched Sputnik and early Luna (and Yuri Gagarin), however with the mannequin title Atlas, the USA’s iconic missile/rocket that launched Mercury missions (like John Glenn) and the Mariner probe.

DivKid did a launch video that includes the brand new module which works by quite a lot of its sound design prospects – significantly that morphing scanner, which you really want to listen to:

Stazma did some patching work with it too:

Good Circuit has Atlas out there now (on preorder):

When you purchase one thing from a CDM hyperlink, we could earn a fee.

Atlas Quad-Core Multimode Filter

And so they carry the total Vostok vary:

Vostok Devices @ Good Circuit

And I can’t point out Atlas with out watching the current-generation Atlas V launch the Perserverance rover to Mars from the Cape.

And the view from the rocket:


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